1. Field of Invention
The present invention relates to a multiple cylinder engine such as a V-type 2-cylinder engine and, more particularly, to a multiple cylinder engine capable of controlling an air/fuel ratio accurately.
2. Description of Related Art
In a small general-purpose engine to be used in an agricultural machine, a small-sized power generator or the like, a carburetor is generally employed in an intake system of the engine. In case there is considered the response of the engine at its acceleration/deceleration, the countermeasures against exhaust emissions of recent years and the homogeneous distribution of mixtures, however, it is thought that a fuel injection device (especially, an electronic control type fuel injection system) for injecting fuel directly into the intake pipe is advantageous over the carburetor. From this background, the fuel injection device is being adopted at present.
Here will be briefly described the construction of the fuel injection device by exemplifying a fuel injection type V-type engine for adjusting a fuel injection quantity by measuring an intake pipe vacuum downstream of a throttle valve and by converting the measured vacuum into an intake air flow. This fuel injection device is constituted, as shown in FIG. 9, to include a fuel injection valve 81, a fuel pressure adjustor 82 and a pressure sensor 83 shared by individual cylinders 80 and 80. An intake passage 84, as shared by the individual cylinders 80 and 80, and the fuel pressure adjustor 82 are connected by conduit 86. The intake passage 84 and the pressure sensor 83 are connected by conduit 85. The pressure sensor 83 has a vacuum inlet port 85a, which is opened into the intake passage 84 downstream of a throttle valve 87.
In the case of this constitution, the intake pressure is averaged conveniently for the fuel pressure adjustor 82, even if it is introduced from the intake passage 84 shared by the two cylinders into the single fuel pressure adjustor 82. As the peaks of the intake pressure of the intake pipe are excessive close on the time axis, however, they are unclear for the pressure sensor 83 to detect, so that the accuracy of the injection quantity control is deteriorated.